What would be considered the climax in The Report Card?

Andrew Clements's novel The Report Card follows the attempts of Nora, the fifth-grader protagonist, to question the grading system so institutional to American schooling and to get the adults around her to reconsider what education means.
Despite being a genius, Nora intentionally gets all Ds and a C on her report card for the first term of fifth grade in order to make a point about how problematic grades are. Nora detests the performance aspect of intelligence, and, thus, she hides her smarts so that she can remain in control of them and to avoid attention.
The purposeful failure of her classes ends up backfiring in that regard, as Nora receives more attention than ever. Teachers start to hover over her, and she is called into the principal's office to meet with her teachers, guidance counselor, the principal, and her parents. When Mrs. Byrne, the school librarian, checks Nora's Internet history and discovers the advanced materials she had been reading and researching after school, Nora comes clean to the woman and explains that her grades do not matter because she can turn them around anytime she wants.
Nora is eventually outed as a genius when her guidance counselor gives her an intelligence test. This brings on even more pressure and attention from her family, the school, and the other students. Eventually, Nora and her friend Stephen formulate a plan to show the school how ridiculous grading and competition are: Nora demonstrates her intelligence to the whole class and then intentionally gets zeroes on all her tests the next day, commenting that every child in the school should be learning more stimulating material rather than just being asked to memorize facts.
The climax of the novel occurs when it is revealed that Stephen has put the second part of their plan into place by convincing almost all of the students in Nora's class to score zeroes on their tests as well. The principal and school superintendent are horrified and want to suspend them, claiming that this plan is like an act of vandalism. However, Mrs. Byrne speaks out in their defense, as do other teachers. After discussing her efforts with her fellow students, Nora comes to the realization that the teachers also want to see the educational system improve and that it is much more effective to do so by working rather than intentionally flunking.